Measurement of thermal transients in semiconductor power devices and circuits

A method for measuring microsecond thermal transients in devices and circuits is described and used to study the behaviour of commercially available low power (1 W) transistors. The results are used to demonstrate the usefulness of the method and show some agreement with previously published theoretical data. Hot spots which move from site to site on interdigitated bipolar transistor structures have been observed. The form of the thermal transient is dependent on the values of collector current and voltage, and the site of eventual breakdown of the device depends on these two quantitites.